(a) Field of the Invention
This invention relates to a syringe useful in extruding a semi-plastic, particulate mass therefrom.
(b) Information Disclosure Statement
The use of two component mixing syringes for dissolving a solid medicament in a liquid diluent prior to injection of the solution is well known in medical practice. An example of such syringes is illustrated by Lindberg et al. U.S. Pat. No. 4,060,082, which describes a syringe combination comprising a mixer/dispenser syringe, usually containing a solid medicament, which is connected via a collapsible connecting sleeve to a carrier syringe, usually containing a liquid diluent used to dissolve the medicament in the mixer/dispenser section. When it is desired to use the syringe, the two syringe sections are telescoped together thus forcing a fill needle positioned between the two syringe sections to make a communicating connection between the mixer/dispenser and the carrier syringe sections. The liquid contents of the carrier section can then be ejected through the fill needle into the mixer/dispenser section. After the solid medicament has dissolved, a hypodermic needle is attached to the exit end of the mixer/dispenser section, a plunger is attached to a rubber piston closing the other end, and the liquid contents can then be ejected.
There are various means for making connection between two sections of a two component mixing syringe, the collapsible sleeve and filling needle described in the above-noted Lindberg et al. patent being one such means. Another means of achieving such inter-connection is illustrated in Choksi et al. U.S. Pat. No. 4,046,145 which describes a Luer lock/Luer joint two-part unit.
However, syringes for dispensing liquids are difficult to use in the extrusion of semi-plastic, particulate masses, and may in some cases be inoperative for such purpose. While the prior art is thus instructive on the problem of mixing two components and dispensing a resulting solution in liquid form, so far as is known, the art is silent on the problem of mixing two or more components within a syringe barrel, so as to form a semi-plastic, particulate mass, for extrusion thereof.
It has been found that particulate matter, such as particulate ceramic material used in dental restorative procedures, even when wetted, tends to jam in the barrel when extruded from conventional syringes, perhaps due to frictional resistance between the sharp edges of the particles and the syringe barrel wall. I have discovered that the problem can be overcome by equipping the syringe barrel, which is advantageously fabricated of a flexible plastic material, with one or more longitudinal slits in the barrel. The provision of such slits has the effect of providing sufficient relief from the frictional resistance to permit unobstructed extrusion of particulate material from the barrel.